21001200122121 has 8 divisors (see below), whose sum is σ = 28001664949920. Its totient is φ = 14000767687872.

The previous prime is 21001200122117. The next prime is 21001200122171. The reversal of 21001200122121 is 12122100210012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21001200122121 - 2² = 21001200122117 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21001200122121.

It is not an unprimeable number, because it can be changed into a prime (21001200122101) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6542976 + ... + 9209393.

It is an arithmetic number, because the mean of its divisors is an integer number (3500208118740).

Almost surely, 2^{21001200122121} is an apocalyptic number.

It is an amenable number.

21001200122121 is a deficient number, since it is larger than the sum of its proper divisors (7000464827799).

21001200122121 is a wasteful number, since it uses less digits than its factorization.

21001200122121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16196775.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21001200122121 its reverse (12122100210012), we get a palindrome (33123300332133).

The spelling of 21001200122121 in words is "twenty-one trillion, one billion, two hundred million, one hundred twenty-two thousand, one hundred twenty-one".